Method and apparatus for blind riveting

ABSTRACT

A tubular rivet having a preformed head and a shank which extends through aligned apertures of workpiece members is set by expanding the end of the shank remote from the head to form a blind head by pulling the head of a mandrel into the bore of the shank. Then the shank together with the blind head and a central portion of the preformed head is moved in a direction towards the preformed head while restraining movement of the periphery of the preformed head, thereby deforming the preformed head and decreasing the distance between the preformed head and the blind head. An anvil for a rivet setting tool has an annular abutment for engaging the periphery of the preformed head of the rivet and a recess into which the central portion of the preformed head can enter when it is deformed.

United States Patent Davis et al.

[451 Sept. 24, 1974 METHOD AND APPARATUS FOR BLIND RIVETING Avdel Limited, Hertfordshire, England Filed: Feb. 13, 1973 Appl. No.: 332,126

Assignee:

[30] Foreign Application Priority Data Feb. 14, 1972 Great Britain 6823/72 US. Cl 72/391, 29/509, 72/406 Int. Cl B2ld 9/05 Field of Search 72/391, 406; 85/77, 82;

References Cited UNITED STATES PATENTS 3,187,546 6/1965 Simmons ..72/391 3,657,957 4/1972 Siebol ..85/77 FOREIGN PATENTS OR APPLICATIONS A .P. C,, S.N. 190868, J.F.G. Chobert, published June 15, 1943.

A.P.C., 286712, J.F.G. Chobert, published June 8, 1943.

Primary Examiner-Charles W. Lanham Assistant ExaminerJames R. Duzan Attorney, Agent, or Firm-Oblon, Fisher, Spivak, McClelland & Maier [5 7] ABSTRACT A tubular rivet having a preformed head and a shank which extends through aligned apertures of workpiece members is set by expanding the end of the shank remote from the head to form a blind head by pulling the head of a mandrel into the bore of the shank. Then the shank together with the blind head and a central portion of the preformed head is moved in a direction towards the preformed head while restraining movement of the periphery of the preformed head, thereby deforming the preformed head and decreasing the distance between the preformed head and the blind head.

An anvil for a rivet setting tool has an annular abutment for engaging the periphery of the preformed head of the rivet and a recess into which the central portion of the preformed head can enter when it is deformed.

10 Claims, 13 Drawing Figures PAIENTEDSEPZMW 3', e37; 208

SHEET u 0F 5 PAIENTED 3, 887. 208

SHEET S DF 5 METHOD AND APPARATUS FOR BLIND RIVETING This invention relates to riveting and more particularly to a method and apparatus suitable for blind riveting which enable workpiece members which are spaced apart to be drawn closely together during the operation of riveting them together.

According to the present invention there is provided a method of riveting for fastening together apertured members by means of a tubular rivet having a shank and a preformed head at one end of the shank, using a mandrel having an enlarged head for setting the rivet, which method comprises inserting the rivet shank through aligned apertures in members to be fastened together, pulling the mandrel head into the bore of the rivet shank to form a blind head at the end thereof remote from the preformed head and then deforming the preformed head of the rivet so as to draw the workpiece members relatively towards each other without axially contracting the rivet shank. After deforming the preformed head of the rivet to draw the workpiece members relatively towards each other, the mandrel head may be pulled further into the bore of the rivet shank to cause axial contraction of the rivet shank.

According to another aspect of the invention there is provided a method of riveting apertured workpieces together by means of a tubular rivet having a shank and a preformed head at one end of the shank, comprising inserting the rivet shank through aligned apertures of the workpiece members to be fastened together, deforming the rivet shank to produce a blind head at the end of the shank remote from the preformed head and then deforming the preformed head of the rivet towards the blind head so as to force the members of the workpiece together.

According to another aspect of the invention, there is provided apparatus for use in setting a tubular blind rivet having a shank and a head, which apparatus comprises an anvil having a recess which, in use of the anvil, is adapted to overlie the central portion (as hereinafter defined) of a rivet head in spaced relation thereto, and an abutment peripherally of the recess adapted initially to engage the rivet head peripherally of the central portion thereof, whereby the rivet head can be deformed to cause part of the central portion thereof to enter the recess.

The term central portion used herein in relation to a rivet head means a portion of the rivet head which is axially aligned with the shank of the rivet and of which the diameter is less than the diameter of the rivet head and greater than the diameter of the shank of the rivet at the point where the shank joins the head.

The anvil may be constructed as two cooperating semiannular portions and these portions may be constructed to operate as jaws of a repetition riveting tool of the kind in which a plurality of rivets are carried on a mandrel and are fed in succession past a pair ofjaws towards the head of the mandrel and in which the jaws then close behind the leading rivet to form an abutment for the rivet which takes up the reaction of forces produced on drawing the head of the mandrel into the bore of the rivet.

The invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is an elevation of a tubular blind rivet which is particularly suitable for riveting by the method of the invention;

FIG. 2 is an elevation of one of a pair of cooperating jaws of riveting apparatus embodying the invention;

FIG. 3 is a fragmentary sectional elevation through a pair of the jaws shown in FIG. 2;

FIGS. 4 to 8 illustrate successive stages in the setting of the rivet of FIG. 1 by the method according to the invention and using an anvil according to the invention, and

FIGS. 9 to 13 illustrate, for comparison with FIGS. 4 to 8, the setting of the rivet of FIG. 1 in a conventional manner using a conventional anvil.

Referring now to FIG. 1, a tubular blind rivet 10 comprises a shank 11 with a radially enlarged preformed head 12 at one end (the head end). A portion of the shank adjacent the other end thereof (the tail end) is of increased external diameter providing a tail portion 13. A portion of the shank adjacent the head increases in external diameter to the point at which it meets the head, providing a conical portion 14. The shank has a cylindrical intermediate portion 15 between the conical'portion and the tail portion 13. The rivet has a bore 16 which extends throughout the length of the rivet, passing axially through the head and shank. In the region of the tail portion 23 and the intermediate portion 15, the bore is of substantially constant diameter so that the intermediate portion has a constant wall thickness. In the region of the conical portion 14 however, the diameter of the bore increases towards the head so that the bore flares. The angle at which the bore flares is such that the wall thickness of the conical portion is the same as that of the intermediate portion of the shank.

' The upper surface 17 of the head 12 (that is, the surface remote from the shank 11) is convexly curved. The underside 18 of the head of the rivet (that is the side towards the shank 11) is formed with an annular flat face 19 which lies in a plane at right angles to the shank and which extends radially inwardly from the peripheral edge 20 of the head, to an annular recess 22 between the shank and the flat face 19.

Referring now to FIGS. 2 and 3, an annular anvil 30 according to the invention (FIG. 3) for a repetition riveting tool comprises a pair of identical semi-annular jaws 32, 34 which cooperate together.

As shown in FIG. 2, each jaw is elongate and of generally semi-cylindrical shape, having at one end an outwardly projecting flange 36 and, spaced therefrom towards the other end, external rib 38. The flange 36 and rib 38 are provided to enable the jaws to be located in and operated by the power unit (not shown) of a conventional repetition riveting tool. Each jaw has a radially inwardly projecting flange 40 at the end 42 remote from the flange 36.

The faces defined by the ends 42 of two of the jaws in co-operation form an annular anvil face for abutting the upper surface 17 of the head of a tubular rivet during a rivet setting operation. A central aperture 44 in the anvil face allows the stem of a mandrel used for setting rivets to extend between the jaws. The anvil face comprises an annular abutment surface 46, and, between the abutment surface 46 and the central aperture 44, a concavely dished surface 48 which, together with the central aperture, defines a recess centrally of the annular abutment surface 46.

The dimensions of the anvil face are such that the abutment surface 46 can abut the periphery of the head of a tubular rivet axially aligned with the anvil, the concavely dished face overlying the central portion of the rivet head and, in the case of an unplaced rivet, being spaced therefrom since the radius of curvature of the dished face is smaller than the radius of curvature of the upper surface of the rivet head.

In this embodiment, the relevant dimensions (in inches) of the anvil face are as follows:

Diameter of Central aperture-0.191

Diameter of dished face-0.280 to 0.275

Diameter of abutment surface-0.470 (Minimum) Radius of curvature of dished face-0.300 v This anvil is suitable for placing, in accordance with the invention, a tubular rivet as described with reference to FIG. 1 of which the relevant dimensions are as follows:

Diameter of head-0.36 to 0.38

Maximum external diameter tion-0.185 to 0.190

Maximum diameter of bore-0.157

Radius of curvature of upper surface of head-0.55

of conical por- External diameter of intermediate portion of shan- Maximum external diameter of tail portion0.l88

The behaviour of the rivet during setting in accordance with the invention will now be described.

Referring now to FIGS. 4 to 8 and FIGS. 9 to 13, two apertured sheet members 50, 52 which are to be fastened together, constitute a workpiece. The total thickness of the sheets 50, 52 is less than the maximum thickness of workpiece in which the rivet 10 can be used successfully, this condition being indicated in the drawings by the fact that the member 52 is thinner than the member 50. It will however be noted that the members 50, 52 which are to be fastened together are initially spaced apart (FIGS. 4 and 9) and in fastening them together, it is desired to draw them closely together.

As shown in FIGS. 4 and 9, the members 50, 52 are assembled with their apertures aligned and the rivet 10 is positioned with its shank 11 extending through the aligned apertures, the tail portion 13 projecting from one side of the assembled members and the head 12 abutting the other side of the assembled members. In FIG. 4, the pair of jaws 32, 34 constituting an annular anvil according to the invention of a riveting tool are shown disposed in engagement with the upper surface 17 of the rivet head and it will be seen that the concave dished surface overlies, and is spaced from, the central portion of the rivet head over an area of larger diameter than the maximum diameter of the conical portion of the shank, the upper surface 17 of the head being engaged by a region of the anvil at the intersection of the concavely dished surface and the annular abutment surface at a position radially outwardly of the central portion of the rivet head.

In FIG. 9, an exactly similar arrangement to that of FIG. 4 is shown except that a conventional annular anvil having a flat anvil face with no recessed or concavely dished surface, engages the upper surface 17 of the rivet head in the central portion thereof which overlies the conical portion of the shank.

A mandrel 60 having a stem 62 and an enlarged head 64 at one end of the stem and forming part ofa riveting tool extends through the central aperture of the conventional annular anvil and through the bore of the rivet, the head of the mandrel projecting beyond the tail end of the rivet.

FIGS. 5 to 8 and 10 to 13 illustrate the performance of the rivet 10 as the mandrel is drawn progressively into the bore of the rivet from the tail end thereof. In FIGS. 5 to 10 the head of the mandrel has begun to enter the tail portion of the rivet expanding it radially outwardly to form a blind head which engages with the sheet 52 on the side thereof remote from the sheet 50 (the blind side).

It will be seen in FIG. 6 that, as the mandrel continues to be pulled towards the anvil, the mandrel head does not enter appreciably further into the bore of the rivet, but instead displaces the shank towards the anvil, causing the rivet head to become deformed so that the central portion thereof enters into the recess in the anvil face and abuts the concavely dished surface 48. It will also be seen from FIG. 6 that, due to the engagement of the expanded tail portion or blind head with the sheet 52, the sheet 52 is drawn towards the anvil while the sheet 50 remains in its original position relative to the anvil due to the fact that it is in abutment with the peripheral portion of the rivet head which in spite of the deformation of the rivet head, has not changed its position relative to the anvil.

Thus by using an anvil according to the invention, the deformation of the rivet head to the shape shown in FIG. 6 has caused a reduction in the distance separating the members 50 52 before the mandrel has begun to expand the intermediate portion of the shank to cause it to contract axially. Once the rivet head has been deformed into abutment with the concavely dished surface of the anvil, continued movement of the mandrel causes the mandrel head to begin again to pass through the bore of the rivet as shown in FIG. 7 so that the resulting radial expansion of the intermediate portion of the shank causes the shank to contract axially and thus to reduce still further the distance separating the members 50, 52 until, as shown in FIG. 8, the rivet shank has been expanded throughout its length and is fully axially contracted.

In contrast to this however, the use of a conventional anvil does not permit deformation of the rivet head and consequently the rivet shank cannot move towards the anvil. Consequently the progressive movement of the mandrel causes a correspondingly progressive entry of the mandrel head into the bore of the rivet. As shown in FIG. 11 therefore, at the same stage of relative movement between the mandrel and the anvil as in FIG. 6, the head of the mandrel begins to expand the intermediate portion of the shank radially outwards into engagement with the workpiece members. This radial expansion causes the shank to contract in the axial direction in the region between the blind head and the preformed head 12 and causes some reduction in the distance separating the members 50, 52. This action is continued as the mandrel passes further along the bore (FIG. 12) until, as the mandrel leaves the bore of the rivet at the head end, the rivet shank has undergone the maximum amount of axial contraction but a gap still remains between the members 50, 52.

It will be appreciated that the axial contraction of the rivet shank due to its radial expansion by passage of the mandrel, is not affected .by the type of anvil used. Thus the extent to which the members 50, 52 are drawn together due to axial contraction of the shank is the same in the process illustrated in FIGS. 4 to 8 as in that illustrated in H68. 9 to 13. In the process of FIGS. 9 to 13, this contraction is inadequate to draw the members 50, 52 entirely together whereas when the anvil of the invention is used, the initial closing of the members 50, 52 obtained by deforming the rivet head is such that the ensuing contraction of the shank is adequate to draw the members 50, 52 into abutment with each other as shown in FIG. 8.

This invention is not limited to the details of the foregoing embodiment. For example, instead of the anvil surface having a concavely dished surface, the recess may be stepped inwardly from the abutment surface of the anvil faces.

We claim:

1. A method of blind riveting for fastening and drawing spaced apertured workpiece members tightly together by means of a tubular rivet having a shank and a preformed head at one end of the shank, which method comprises inserting the rivet shank through aligned apertures of the workpiece members to be fastened together so that the preformed head abuts one of the workpiece members, deforming the rivet shank to produce a blind head at the end of the shank remote from the preformed head and then deforming the preformed head of the rivet so as to move a peripheral portion thereof relative to a central portion of the preformed head in a direction towards the blind head and thereby forcing the members of the workpiece together.

2. A method of blind riveting accordingto claim 1, wherein the preformed head is deformed by moving the blind head and the shank and a central portion of the preformed head of the rivet relatively in a direction towards the preformed head, while the peripheral portion of the preformed head is maintained in relatively the same position.

3. A method of blind riveting according to claim 1, wherein the blind head is formed by pulling a mandrel into the bore of the rivet and the preformed head of the rivet is then deformed by engaging a peripheral portion of the preformed head with an abutment relative to which the mandrel is movable, and then moving the mandrel relatively towards the abutment so as to move the shank with the blind head and the central portion of the preformed head in a direction towards the abutment.

4. A method of blind riveting according to claim 3,

wherein the abutment is part of an anvil adapted to engage a peripheral portion of the preformed head and having a recess adapted to overlie a central portion of the preformed rivet head in spaced relationship thereto, the abutment being arranged to engage the preformed head at a position such that the force required to deform the rivet head is greater than that required to cause the mandrel to deform the shank to form a blind head.

5. A method of blind riveting according to claim 1, wherein after the preformed head has been deformed, the shank of the rivet is radially expanded throughout its length and thereby causing the shank to contract in the axial direction so as to draw the preformed head and the blind head together.

6. A method of riveting and drawing together apertured workpieces by means of a tubular rivet having a shank and a preformed head at one end of the shank, which method comprises inserting the rivet shank through aligned apertures in workpiece members to be fastened together, deforming the rivet shank to produce a blind head at the end of the shank remote from the preformed head, and then deforming the preformed head so as to reduce the distance between a peripheral portion of the preformed head and the blind head.

7. A method according to claim 6, wherein the preformed head is deformed by moving the shank together with the blind head and a central portion of the preformed head relatively towards the preformed head while maintaining the peripheral portion of the preformed head in relatively the same position.

8. A method according to claim 7, wherein a mandrel is pulled into the end of the rivet remote from the preformed head to form the blind head and to draw the blind head into abutment with the workpiece, and the peripheral portion of the preformed head is engaged by an abutment for taking up the reaction of forces consequent upon pulling the mandrel into the bore and maintaining the peripheral portion of the head in relatively the same position.

9. A method according to claim 8, wherein after deforming the preformed head, the mandrel is drawn entirely through the bore of the rivet in the direction towards the rivet head.

10. A method according to claim 6, wherein after deforming the preformed head, the shank of the rivet is caused to contract in the axial direction. 

1. A method of blind riveting for fastening and drawing spaced apertured workpiece members tightly together by means of a tubular rivet having a shank and a preformed head at one end of the shank, which method comprises inserting the rivet shank through aligned apertures of the workpiece members to be fastened together so that the preformed head abuts one of the workpiece members, deforming the rivet shank to produce a blind head at the end of the shank remote from the preformed head and then deforming the preformed head of the rivet so as to move a peripheral portion thereof relative to a central portion of the preformed head in a direction towards the blind head and thereby forcing the members of the workpiece together.
 2. A method of blind riveting according to claim 1, wherein the preformed head is deformed by moving the blind head and the shank and a central portion of the preformed head of the rivet relatively in a direction towards the preformed head, while the peripheral portion of the preformed head is maintained in relatively the same position.
 3. A method of blind riveting according to claim 1, wherein the blind head is formed by pulling a mandrel into the bore of the rivet and the preformed head of the rivet is then deformed by engaging a peripheral portion of the preformed head with an abutment relative to which the mandrel is movable, and then moving the mandrel relatively towards the abutment so as to move the shank with the blind head and the central portion of the preformed head in a direction towards the abutment.
 4. A method of blind riveting according to claim 3, wherein the abutment is part of an anvil adapted to engage a peripheral portion of the preformed head and having a recess adapted to overlie a central portion of the preformed rivet head in spaced relationship thereto, the abutment being arranged to engage the preformed head at a position such that the force required to deform the rivet head is greater than that required to cause the mandrel to deform the shank to form a blind head.
 5. A method of blind riveting according to claim 1, wherein after the preformed head has been deformed, the shank of the rivet is radially expanded throughout its length and thereby causing the shank to contract in the axial direction so as to draw the preformed head and the blind head together.
 6. A method of riveting and drawing together apertured workpieces by means of a tubular rivet having a shank and a preformed head at one end of the shank, which method comprises inserting the rivet shank through aligned apertures in workpiece members to be fastened together, deforming the rivet shank to produce a blind head at the end of the shank remote from the preformed head, and then deforming the preformed head so as to reduce the distance between a peripheral portion of the preformed head and the blind head.
 7. A method according to claim 6, wherein the preformed head is deformed by moving the shank together with the blind head and a central portion of the preformed head relatively towards the preformed head while maintaining the peripheral portion of the preformed head in relatively the same position.
 8. A method according to claim 7, wherein a mandrel is pulled into the end of the rivet remote from the preformed head to form the blind head and to draw the blind head into abutment with the workpiece, and the peripheral portion of the preformed head is engaged by an abutment for taking up the reaction of forces consequent upon pulling the mandrel into the bore and maintaining the peripheral portion of the head in relatively the same position.
 9. A method according to claim 8, wherein after deforming the preformed head, the mandrel is drawn entirely through the bore of the rivet in the direction towards the rivet head.
 10. A method according to claim 6, wherein after deforming the preformed head, the shank of the rivet is caused to contract in the axial direction. 